This invention relates to a gas-blast electric circuit breaker which relies upon a pump, or puffer, for forcing a blast of relatively cool gas into the arcing region of the breaker to promote arc extinction.
My U.S. Pat. No. 3,739,125, assigned to the assignee of the present invention, discloses and claims a puffer type circuit breaker comprising: (i) a pair of spaced electrodes between which an arc is established, (ii) a nozzle of insulating material having a throat through which the arc extends during interruption, and (iii) means for forcing a blast of arc-extinguishing gas into the arcing region during interruption.
Improved circuit interrupting performance is obtained in this circuit breaker by injecting the arc-extinguishing gas via a plurality of radially-extending injection passages leading into the throat of the nozzle and forcing this gas to flow axially of the arc in opposite directions from the throat toward the spaced electrodes.
In my aforesaid patent, the pump used for injecting the arc-extinguishing blast comprises a cylinder and piston surrounding the nozzle and defining an annular cylinder space also surrounding the nozzle. While such a cylinder and piston arrangement is relatively simple and is in a location where it does not interfere with the desired flow pattern for the arc extinguishing blast, an interrupter that utilizes such a pump is subject to certain disadvantages.
One such disadvantage is that this pump consumes a relatively large amount of space considered radially of the nozzle, and this requires that the interrupter housing have an unduly large diameter. Another disadvantage is that the parts of the pump, being situated between the spaced electrodes, must generally be of insulating material to avoid impairing the dielectric strength prevailing between the electrodes. This requirement results in a more expensive pump as compared to one that has mostly metal components.
Still another disadvantage of the aforesaid prior construction is that an involved linkage is needed for interconnecting the movable pumping element and the movable contact of the circuit breaker in order to actuate the pumping element in response to movement of the contact.